I bought this 1991 firebird in like Oct 2012 and I finally getting around to working on it. The previous own told me he did a tune up on the vehicle then he started having problem with it stalling out on him after in runs for a few minutes. He then did another tune up fix the problem for a few weeks then it did it again. He took it to his mechanic who told him he was having a timing problem and had that the chain slipped, he started to replace the timing chain but then the old owner told im not too becuase he could afford it. He let it sit for a few months and this is when I bought it for $600.

Problems it had:
Car started only twice and would run for about 5 seconds then shut off. Ran really rough for the few seconds.
Gas mixed with oil in Oil Pan when i drained it.
When car was at TDC the distributor rotor was at #4 firing postion.

Codes: 12, 15, 43

What I've done:
New Battery
Oil Change
New Knock Sensor
Added Sea Foam to Gas
Replace Fuel Pump Fuses wasn't working when tested before (I hear fuel Pump running when key is in on position)
New Fuel filter.
New Water Pump
New Timing chain, Set the timming manually (since wont run) by turning crank manual to TDC. I then repositioned the Distributor and rotor to make #1 in firing postion:

Now Code 12, 43

Still cranks but doesn't want to turn over. I now hear like a slight backfire or pop in the exhaust.
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Smurfdaddy52

 

I'm not an expert, but I did a search on code 43 and found this which may help. It is in response to someone with a 1991 Camaro V6. I'm sure other forum members with more experience will also post suggestions. Good Luck.

BTW - ECM is the Engine Control Module, which is the car's computer. It is a very basic computer; not like a modern vehicle's sophisticated and expensive engine computer.

WOT - wide open throttle

Jiffy did an Archive search & found this from spearson

Code 43 -- ESC electronic spark control module. Electronic spark control is accomplished with a module that sends a voltage signal to the ECM. When the knock sensor detects engine knock, the voltage from the ESC module to the ECM drops and this signals the ESC to retard timing. The ECM will retard the timing when the knock is detected and rpm is above about 900 rpm. Code 43 means the ECM has been low voltage at CKT 485 terminal "B7" for longer than 5 seconds, with the engine running or the system has failed the functional check. This system performs a functional check once per start up to check the ESC system. To perform this test the ECM will advance the spark when when coolant is above 95 degrees C(194 Degrees F) and at a high load condition ( near WOT). The ECM then checks the signal at "B7" to see if a knock is detected. The functional check is performed once per start up and if a knock is detected when the coolant is below 95 C then the test has passed and the functional check will not be run. If the function check fails, the SES light will remain ON until the ignition is turned OFF, or until a knock signal is detected.
Ok to test the stuff out to find what is wrong do this.1.

· Clear Codes
· idle engine for 1 minute or
until a SES light comes ON
· read new codes


No code 43This test will dtermine if the system is functioning at this time. Usually a knock signal can be generated by tapping on the right exhaust manifold. If no knocksignal is generated, try tapping on the block next to the area of the sensor. Follow the following steps.

· run engine at about 1500 RPM
· trans in park/nuetral and at normal
operating temp
· tap engine block in area of knock
sensor and check for rpm drop

If the RPM drops the problem is intermittent, if there is no rpm drop then there is no problem But if you do get a code 433.with the engine idling check terminal B7 with a VOLTMETER to a ground and note the voltage If over 6 volts it is a faulty connection at ECM terminal B7 or ECM. If under 6 volts do the following

4. Ignition on, but engine stopped, recheck the voltage at ECM terminal B7. If over 6 volts change the ESC module. If under 6 volts do the following

5. Ignition off disconnect ECM "A-B" connector turn ignition on and recheck voltage. If over 6 volts Replace the ECM. If under 6 volts do the following

6. Disconnect ESC module. check voltage from ESC connector terminal B to ground. It should read battery voltage (12 volts). If not OK, repair open in CKT 439. If OK do the following, Check for open or short to ground in CKT 485. If not open or shorted to ground, it is a faulty ESC connection or ESC module. I hope some of that can help ya. I also got the code once but it was from some bad gas.

https://www.thirdgen.org/forums/v6/6...what-does.html

It may be something as simple as a loose ground wire.

BTW - did you drain the old gas and put in fresh gas?

 

I reset the timing manually again and got the engine to run for about 10 seconds. It ran very rough then cut off. I got it to run again about 3 more times for only maybe 5 seconds each time. I think I killed my battery in the process.

I already replace knock sensor as I stated early. Once again I code a code 15 now along with the 43. Tight on cash so don't have much to spend. Just trying to avoid ripping the plenum off to replace injectors. I an beginner Do-it-yourselfer so go easy on me.

 

Have you performed a compression test? There could of been some inference if the timing chain slipped. I'd do that before replacing anything else.

The plenum is actually really easy to remove but you don't need to pull it to check your injectors. There's a 6 position connector under the throttle body to the right a little. Disconnect that connector and test the resistance between the pink wires and the blue and green ones.

Other things to look at are the ignition control module and coil. Auto Zone will test your ICM for free. What happens if you shoot some carb spray into the throttle body? does it try to start any better?

 

I have not done a compression test.

I know the plenum is not hard to remove. good info about the connector under the TB. What the resistance suppose to be? Am i Suppose to leave it connected when I test the resistance or disconnect the plug from the other side.

I'll have to look into the ICM and coil thing with Auto Zone I was just there earlier today I'll check with them tomorrow

 

If your ignition control module (ICM) is bad, a new ICM will come with a small tube/packet of heat resistant grease. Be sure to smear the grease on the metal plate on the bottom side of the ICM. If you don't, it will go bad quickly. The clerk at the auto store can show you where to put the grease if you are not sure.

 

FYI - error code 15 indicates a problem related to the coolant sensor circuit.

There could be:
*Faulty or loose wiring and/or connectors from the coolant sensor.
*Faulty coolant sensor.
*Faulty or loose wiring and/or connections at the ECM.

It can be a PITA trying to track down what needs to be repaired. Keep posting updates. If you still can't diagnose the problem, I'm sure one of the senior experts will offer other steps you can take to diagnose.

 

A code 43 can also indicate a Throttle Position Sensor (TPS) problem. Have you tried pumping the throttle when you try starting the engine? You're not supposed to pump the throttle, but a TPS or timing problem may help the engine start by pumping the throttle.

I replaced the whole distributor on my '92 bird 3.1L and it's a little out of time. It starts if I pump the throttle. I borrowed a friend's Snap-on timing light and will fix the timing. Biggest problem is getting a socket down onto the bolt to loosen the distributor. It's in a tight spot and I'll probably need to use a universal and definitely an extension. Clumsy as I am, I'll probably drop the socket several times before I get it on the bold. My fat hands don't help either trying to guide something into a tight area.

 

Disconnect the connector and make sure you test the side leading to the injectors. They should come out to around 4 ohms or so. I believe 6 or higher is bad.

You can rent a compression tester from Auto Zone. They'll tell you exactly how to use it. I'd be concerned about internal damage if the timing chain jumped. I had a similar situation that ended in bent exhaust valves.

It's all a process of elimination really. Have you tested your fuel pressure?

 

Got 4ohms on one and 3ohms on the other.

Not fuel pressure test yet.